NAP, an 8-amino-acid peptide (NAPVSIPQ=Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln) (SEQ ID NO:1), is derived from activity-dependent neuroprotective protein, ADNP (U.S. Pat. No. 6,613,740, Bassan et al., J. Neurochem. 72: 1283-1293 (1999)). The NAP sequence within the ADNP gene is identical in rodents and humans (U.S. Pat. No. 6,613,740, Zamostiano, et al., J. Biol. Chem. 276:708-714 (2001)).
In cell cultures, NAP has been shown to have neuroprotective activity at femtomolar concentrations against a wide variety of toxins (Bassan et al., 1999; Offen et al., Brain Res. 854:257-262 (2000)). In animal models simulating parts of the Alzheimer's disease pathology, NAP was protective as well (Bassan et al., 1999; Gozes et al., J. Pharmacol. Exp. Ther. 293:1091-1098 (2000); see also U.S. Pat. No. 6,613,740). In normal aging rats, intranasal administration of NAP improved performance in the Morris water maze. (Gozes et al., J. Mol. Neurosci. 19:175-178 (2002). Furthermore, NAP reduced infarct volume and motor function deficits after ischemic injury, by decreasing apoptosis (Leker et al., Stroke 33:1085-1092 (2002)) and reducing damage caused by closed head injury in mice by decreasing inflammation (Beni Adani et al., J. Pharmacol. Exp. Ther. 296:57-63 (2001); Romano et al., J. Mol. Neurosci. 18:37-45 (2002); Zaltzman et al., NeuroReport 14:481-484 (2003)). In a model of fetal alcohol syndrome, fetal death after intraperitoneal injection of alcohol was inhibited by NAP treatment (Spong et al., J. Pharmacol. Exp. Ther. 297:774-779 (2001); see also WO 00/53217). Utilizing radiolabeled peptides these studies showed that NAP can cross the blood-brain barrier and can be detected in rodents' brains either after intranasal treatment (Gozes et al., 2000) or intravenous injection (Leker et al., 2002) or intraperitoneal administration (Spong et al., 2001). In animal models of neuronal dysfunction associated with increased tau hyperphosphorylation, NAP protected against tau hyperphosphorylation (Vulih-Shultzman et al., J. Pharmacol. Exp. Ther. 323:438-449 (2007); Matsuoka et al., J. Mol. Neurosci. 31:165-170 (2007)).
Tau is a neuronal microtubule-associated protein. Filamentous tau deposits in neurons or glial cells are the hallmark lesions of neurodegenerative tauopathies, such as Alzheimer's disease, Pick's disease, corticobasal degeneration and progressive supranuclear palsy. Biochemical analyses of Sarkosyl-insoluble tau from brains with tauopathies have revealed that tau deposits in different diseases consisted of different tau isoforms (i.e., all six tau isoforms occur in Alzheimer's disease, four repeat tau isoforms occur in corticobasal degeneration or progressive supranuclear palsy, and three repeat tau isoforms occur in Pick's disease).
Abnormalities in tau function or expression are sufficient to cause filamentous aggregation of hyper-phosphorylated tau and neurodegeneration similar to that seen in sporadic tauopathies. The number of tau inclusions and their regional distribution correlate with clinical symptoms; inhibition of tau aggregation or filament formation in neurons or glial cells may prevent neurodegeneration (Hasegava (2006) Neuropathology, 26:484-490).
Recent studies have identified selectively increased oxidative modifications in beta III tubulin in Alzheimer's disease and suggested that beta III tubulin (the neuronal enriched tubulin subunit) contributes to the neuronal cytoskeletal disruption characteristic of Alzheimer's disease (Boutte et al., Faseb J, 20:1473-1483 (2006)). Further studies suggested differential microtubule assembly properties in beta III-enriched tubulin preparations as compared to other tubulin preparations (Khan and Luduena, Invest New Drugs, 21: 3-13 (2003)) and that tau or other microtubule associated proteins drive beta III microtubule assembly. Beta III tubulin was found to be enriched in cold-adapted microtubules from Atlantic cod (Gadus morhua) where it was found to constitute ˜30% of brain tubulin, which is a high percentage (Modig et al. Cell Motil Cytoskeleton, 42: 315-330 (1999)).
As tauopathy and microtubule modifications underlie many acute and chronic neurodegenerative conditions, developments that affect tubulin-tau interactions and neurofibrillary tangle formation hold promising future in protective drug design.